Installation and Establishment
Core concepts
Most transplant failures trace to planting depth. The root flare must sit at or slightly above grade; dig the hole 2–3 times the root ball width but no deeper than the ball, so the tree does not settle. Remove twine, burlap, and wire basket from the top portion of the ball, cut or shave circling roots on container stock, and backfill with native soil unless the entire planting area is being amended. Water is the limiting factor for the first two to three years; establishment roughly tracks one year per 2.5 cm (inch) of trunk caliper, longer for large B&B stock. Stake only when necessary, with flexible ties, and remove within one or two seasons. Mulch a wide ring, keep it off the trunk, and do not fertilize at planting.
Traps
- 'Dig the hole twice as deep' - false, and a leading cause of settling and suffocation.
- Amending only the backfill in heavy clay creates a bathtub that holds water.
- Burying the root flare; girdling roots often begin in the nursery container.
- Heavy crown pruning at planting to 'balance' the roots - research does not support it.
- Leaving synthetic burlap or baskets in place, or staking permanently.
Worked example
A balled-and-burlapped tree arrives with the flare 8 cm below the top of the ball. Set the ball so the flare sits 2–5 cm above grade (roughly the top 10–20% of the ball above surrounding soil), then slope soil to grade - never mound soil over the flare.
Rule of thumb
Plant high, water deep and infrequently, and mulch wide: correct depth at planting prevents more long-term problems than any aftercare treatment.